Muffler for internal-combustion engines



N v I 1 F. A. NELSON 637 V I MUFFLER FOR INTERNAL COMBUSTION ENGINESFiled April 7. 1922 Patented a... 2,1921.

music: A. mson, or woacssrna, nass'acnusirrra man I03m'rnmrurcomsUs'rIonnnema This invention relates to .mufllers forinternalcombustion engines, and it has for its-- chief object to devise amufller which canbe manufactured very economically and which I willeflectually perform the mufliing operation without creating the.excessive back pressure which is produced in mufllers of the presentcommercial types. y

The nature of the invention will be readily '1 understood from thefollowing description when read in connection with the accompanyingdrawings, and thenovel features will be particularly pointed out iii theappended claims. e

". Referring now to the drawings,

' Figure 1 is a lon 'tudinal cross sectional view of one form 0muflierembodyingthe present invention; 1

Fig. 2 is a longitudinal cross sectional to view of another embodimentof the invention' c y 3 is a view similar toFig. ,2 of-a stillrthermodification;

Figs. 4, 5 and 6 are perspective views-of difierent forms of mutes thatmay be used in the mufller; and p Fig. 7 is an elevation of the .lefthand end of the mufller shown in Fig. 3.

. Referring first to Fig. 1, the form of the invention there shownconsists of a tube 2 of circular cross section having a reduced nipple 3projecting from the left-hand end 7 thereof. Telescoped on theright-hand end of the tube 2 is a tapered tubular member 4 and asimilarly shaped member 5 is joined s to the member 4. The smaller endsof the two tubular sections 4 and 5 are united, as

f clearly shown, the union between these arts,

,and also between the parts 2 and 4, ing made by brazing, welding,riveting, or in any other convenient manner. The arts 4 and 5 form aVenturi tube. The nip 1e 3 is connected to the exhaust pipe 0 the engineso that the gases flow through the mufiler in the direction indicated bythe arrow.

The gases are compresed somewhat as they flow into the constricted artof the Venturi tube 4 and expand vrapi lyas they emerge from saidconstricted portion and flow outwardly through the part 5. I have foundby actual use that this arrangement results in efiectuall muflling theexplosions of the engine. I' ave also found that the back smoothing outthe flow 1m. Serial 11o. 550,211. 7

pressure created in a muflier of this type is substantially less than inmufiiers o the common commercial types. The difference at low engine,speeds is not great, but there is a very substantial diflerence at highengine speeds. The back pressure builds up very rapidly in the common tyof mufliers as the engine speed increases, ift in amuf- 'fieriof thecharacter illustrated, while the back pressure does increase somewhat asthe speed of the engine increases, nevertheless the increase is verymuch slower than'in the w more common ty of mufllers, and it never risesas high in t ismuflier as in other types ofmufliers with which I havebeen able to make comparative tests.

For the urpose of further incre'asingth muflling e ect withoutsubstantially increasing the back pressure, I refer. to use a mute inthe-outlet end of t e Venturitubef This mute may take several diflerentforms but in the construction shown in 1 and 4 itconsists of a hollowcone 7 held in the outlet 5 of; the tube by bolts or rivets, andprovided with a plurality of flanges. 8

which hold the mutespaced from the inner wall of the part 5. It shouldbe noted that the'ap'ex of the cone is located close to the constrictedportion of the Venturi tube, and that the -mute tapers more sharply thanthe outlet 5,1 so that the spacebetween the wall of the outlet and themute gradually grows narrower toward the discharge and of the mufller.This construction is of advantage 'in. silencing the exhaust and in ofgases. through the mufller.

Figs. 5 and 6: show other forms of mutes that may be substituted forthat shownin Figs. 1 and .4, the mute shown in Fig. 5 havin a body 9 inthe general form of a cone, at in this case the elements of thesurface'of'the cone are curves instead of being straightlines. This mutealsois provided with strai ht flanges 10 similar to the flanges 8 of t emute 7. The mute 11, Fig. 6, consists of. a hollow conical body piipvide'd with a series of spiral flanges 12. i ese mutes serve tosmooth out the flow of gases through the muffler and break up theintermittent or .pufly character of this flow. This is particularly truewhen the surface of the mute is slightly concaved, or when spiralflanges are used, such flanges being particularly effective indeflecting the gases and producing a rotary motion of them as they flowthrough the outlet.

In the construction shown in Fig. 2, the

parts 4 and 5, which form the Venturi tube,

are arranged as in Fig; 1, and a mute 7 is located in the outlet endofthe tube. These t shown in Fig. 1 with a mute 18 in the ischarge endthereof, a tube 19 forming the inlet for the Venturi tube. This Venturitube is enclosed in a second tube 20 which forms the inlet' for anotherVenturi tube 21 of the same neral, character as, but somewhat larger tan, the tube 17, this tube 21 also being provided with a mute 22.The'tubes Hand 20 are connected 1 a collar or base 28, Figs. 8 and 7,whic is welded, brazed, or riveted to both tubs, the tube 19 projectincentrally thrgirgh the collar 28. The co ar is perfora as indicated at24, to admit air to the space between the tubes 19 and 20. Air is drawnthrough the perforations by the injector action of the current ofexhaust gases.

This arran ment makes a more silent mufller than t lfoseabove described,and it is also particularly valuable in locations where the mufller mustbe placed closely ad- 'acent to wooden or other parts which mightdamaged or possibly ignited by a very hot mumer. The exterior of themufller may be made even cooler by enclosing the tubes 20 and 21 in anouter cylindrical tube 25 uipped with a tapered nozzle or outlet 26.

is tube may conveniently be made integral with the base or collar 23,the perforations 27 in this member admitting air to the s ace betweenthe tubes 20 and 25.

It wil now be appreciated that this invention rovides an exceedingly aimle form of mu er, and that its very simp icity of construction enablesit to be manufactured verv economicall As above stated, the m or is verye cient, it reduces the'lound of the explosions fully as much as do thecommon commercial types of mufilers, and it creates substantially lessback pressure than do the latter types of mufllers. The arrangement ofVenturi tubes in series as shown for instance in Fi 3, is veryeil'ective in silencing the exp osions of the engine without creatingexcessive back pressure.

While I have herein shown and described the-best embodiment of myinvention which I have so far devised, it will readily be appreciatedthat the invention is susceptible of embodiment in man forms difieringin details of construction mm the form shown.

Having thus'describcd my invention, what I desire to claim as new is 1.A mufiier for internal combustion engines, comprising a tube having aconstriction therein with conver 'ng and diverging sections leading toand cm said constriction, one of said sections serving as an inlet andthe other as an outlet for exhaust gases and a mute positioned in saidoutlet and tapered in the same direction as said outlet} said mute beinspaced from the wall 0 said outlet an having parts cooperating with saidoutlet to deflect the see flow through the ace between said mute an thewall of said outlet.

2. A mufllerfor internal combustion engines, comprising a tube having aconstriction therein with conve 'ng and diverging sections leadin to andom said constriction,'one of ear sections serving as an inlet and theother as an outlet for exhaust and a mute positioned in said outlet andtapared in the same direction as but more sharpl than the walls of theoutlet, said mute aving bearing against the wall of said outlet.

3. A mufller for internal combustion engines, comprising a tube having aconstriction therein with converging and diverging sections leadin toand from said constriction, one of said sections serving as an inlet andthe other as an outlet for exhaust gases, and a mute of a proximatelyconical form positioned in sai outlet with its apex close to saidconstriction and having its surface near its base located closer to thewall of the outlet than at its apex, said mute having parts cooperatingwith the-wall of said outlet to exert a smoothing action on undulaetions in the flow of w through said mufller.

4. A mufier for internal combustion engines comprisin a Venturi tubewith one end serving as t e inlet and the other as the outlet forexhaust gases, a mute positioned in said outlet, and another Venturitube in a portion of which the first Venturi tube is enclosed, wherebythe exhaust gases flow throu h said tubes in series.

5. K mufiler for internal combustion engines, comprisin in combination.a Venturi tube, an inlet to connected with said Venturi tube to conductexhaust gases thereto, a second tube. encircling said tubes and spacedtherefrom, means securing said second tube to the inlet tube andconstructed to admit air around the inlet tube, a Venturi tube at thedischarge end of said second tube, and an outer tube enclosing saidsecond tube and secured thereto, said outer tube providing an air spacearound the second tube.

6. A mutiler for internal combustion enflanges on its outer surface- IIIgines, comprising a tube having a constriction therein with convergingand diverging sections leading to and from said constriction, one ofsaid sections serving as an inlet 5 and the other as an outlet forexhaust gases,

a mute of approximately conical form positioned in said outlet with itsapex close to said constriction, said mute having parts cooperating withthe wall of said: outlet to exert a smoothing action on variations in 10the flow of gases through said outlet, and

a discharge pipe for conducting gases away from said outlet, said pipehaving a reduced orifice for the discharge of the gases.

FREDERICK A. NELSON.

